You can resize the chatbox using some lua. In TS1, it's not possible to do this kind of stuff without re-writing/overloading most of the chatbox function itself - see TSC' code. In TS2, it's actually a bit easier to achieve but still requires some overloading if I remember correctly.
There's no easy, built-in way. I thought about porting ZS' chatbox to TSC (with it, you'd have all those things as convar options), but it was never really worth the effort.